How to reflow leds onto star?

stardustsailor

stardustsailor

Well-Known Member
Positivity said:
Little progress

Stencil looks like a really nice fit. Even the extra frame option I added will come in handy. Just need to trim the frame for a tight fit on star, tape top of stencil in place, then tape on bottom (wear the adhesive out a bit so it doesn't stick too strongly). Then basically put star in frame and stencil should fall into place every time. More practical for larger numbers then lining each one up every time...it's a very precise fit on these tiny osram solder pads...couldn't imagine doing this without a stencil.

And the sinkpad stars are really nice, noticeably thicker than normal. Think I'll be reflowing all my single leds this way if it works out.
Click to expand...
Awesome stencil !
Laser cut ?

I'm sure you will be soon reflowing ,whatever you dream of ..
 
Positivity

Positivity

Well-Known Member
Thanks sds, would have been a lot harder and lower quality without your help.

Stencil is laser cut 3mil. After some reading it seems the thin profile with sac305 will work best. Would of been hard to do that without a stencil.

"stencils are made from high quality durable Polyimide. Although we only recommend 75-100 uses per stencil, members in the community have done as many as 300+ boards with a single solder stencil"
 
SupraSPL

SupraSPL

Well-Known Member
Got some XML2 T4-7A4 (3000K) from aliexpress. These are supposed to be the same LEDs that are in the Onyx Grow, but they only way I could get them was loose. Bought some 20mm XML2 copper stars from eBay $0.70 ea.



I read in one of the Cree PDFs that they use and recommend 63/57 lead solder for reflow. So I just put some flux gel on the copper star and tinned it with 63/57 and the solder pads also. I added a bit more flux gel and positioned the LED over the tinned part of the star, aligning the polarity (the little black dot is the negative side of the LED). Holding the star in a pair of scissors to avoid scratching the bottom or burning my fingers, I applied heat through the solder pad using the solder iron (60W). You can control how fast it heats up easily, but as an experiment on the third one I didn't bother ramping up much at all. The solder melted within 10 seconds and the LED positions itself squarely. Super easy and fast.



Of course this is not the technically correct way to do it, but it does work well. I should have used my 26W iron, I was in no hurry. But now we know that a 60W iron with no ramp up will not crack the LED.
 
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Positivity

Positivity

Well-Known Member
Cool...good to know, I've seen that technique on youtube. There's a few ways to get this done for sure.

I already got a thermostat thingy and some kapton tape to secure it on the stove. Gonna practice with the temps and then give it a go. The osram pads are quite a bit smaller than the xml, be a bit more challenging I think.

Osrams were on back order too so it'll be a little while.
 
stardustsailor

stardustsailor

Well-Known Member
SupraSPL said:
Got some XML2 T4-7A4 (3000K) from aliexpress. These are supposed to be the same LEDs that are in the Onyx Grow, but they only way I could get them was loose. Bought some 20mm XML2 copper stars from eBay $0.70 ea.



I read in one of the Cree PDFs that they use and recommend 63/57 lead solder for reflow. So I just put some flux gel on the copper star and tinned it with 63/57 and the solder pads also. I added a bit more flux gel and positioned the LED over the tinned part of the star, aligning the polarity (the little black dot is the negative side of the LED). Holding the star in a pair of scissors to avoid scratching the bottom or burning my fingers, I applied heat through the solder pad using the solder iron (60W). You can control how fast it heats up easily, but as an experiment on the third one I didn't bother ramping up much at all. The solder melted within 10 seconds and the LED positions itself squarely. Super easy and fast.



Of course this is not the technically correct way to do it, but it does work well. I should have used my 26W iron, I was in no hurry. But now we know that a 60W iron with no ramp up will not crack the LED.
Click to expand...
Supra,just remember to clean the flux residues ,with some IPA (Isopropyl Alcohol ) ,'cause flux residues
can oxidise copper if left uncleaned ...

BTW ,cool technique and super easy ....
Great job !
 
Positivity

Positivity

Well-Known Member
First off..thanks everyone who contributed.

Used chipquik sac 305, fine mesh t5. 48 out of 50 are nice and flat...2 have a small tilt. Those two were initially reversed polarity..so I reflowed..cleaned the pads. The residual solder seemed to leave a tilt. Maybe flux needed for second reflow?

Modulating the heat is easy enough with practice. Harder to find an even heat spot to do multiples at a time. Did 10 at a time after I practiced a few.

Magnifying glass..good tweezers..headlamp..stencil...ALL were essential for these tiny leds. I wouldn't even attempt it without it.

May help cobs..may not. Either way 660s hit a nice sweet spot so I think I'll still integrate them...at least a little.

So if anyone wants osion ssl t3t4 bin...it's doable.

image.jpg
image.jpg
image.jpg
image.jpg
 
stardustsailor

stardustsailor

Well-Known Member
...
Positivity ....
Way much solder ...

Thas is ~ 500um at least ,of solder paste thickness
......Half a milimeter ...maybe even more ...

Maximum has to be ~200 um ...

Thickness has to be ...
Thin ...Very thin ...

And in the middle (thermal) pad ,solder has two be separated in two smaller square pieces ..
You applied too much solder ...
If you drive those led hard ,they won't last for long ...

Although that one looks very well soldered ,shown at the last pic ...

..
You'll do really fine reflows -I'm sure -,with some more experience ...
Congrats !
 
Positivity

Positivity

Well-Known Member
Yes sds..that was too much on that particular one. I got better at using the stencil as I went along...lol. That was one of a few ugly ones.

But wouldn't excess come out the middle? I didn't have any excess coming out of the overflows?

I've seen some where there's a ball at the overflows...I didn't notice any of those
 
Positivity

Positivity

Well-Known Member
They will be run hard..so I'll find out. Funny they recommend separating the middle solder pad in their reflow guide..but the stencil they provide doesn't include that.

Good enough..I think. 90% look really nice and flat. Not raised up or anything
 
salmone

salmone

Well-Known Member
...I encourage you Positivity...;-)

...upsss... in the post...
https://www.rollitup.org/t/grow-project-sun_burns-every-summer.629388/page-3#post-8761159

...the link to pdf...
http://www.i-led.co.uk/PDFs/OSLON-SSL-soldering.pdf
...dont go.....sorry...:evil:
...i try upload this pdf... ...is not achieved in osram site...but I see interesting...:fire:

...all these other... yes.. ...are the application notes on the osram site...

http://www.osram-os.com/Graphics/XPic9/00102538_0.pdf/Further Details on lead free reflow soldering of LEDs.pdf

http://www.osram-os.com/Graphics/XPic9/00102592_0.pdf/Measuring of the Temperature Profile during the Reflow Solder Process.pdf

http://www.osram-os.com/Graphics/XPic5/00102589_0.pdf/Manual Lead-free Soldering of LEDs from OSRAM Opto Semiconductors.pdf

http://www.osram-os.com/Graphics/XPic3/00102550_0.pdf/Handling of Silicone Resin LEDs.pdf

http://www.osram-os.com/Graphics/XPic6/00102535_0.pdf/ESD Protection while Handling LEDs.pdf

http://www.osram-os.com/Graphics/XPic2/00102496_0.pdf/Cleaning of LEDs.pdf

http://www.osram-os.com/Graphics/XPic7/00085509_0.pdf/Recommended Pick and Place Tools (Nozzles) for LEDs of OSRAM Opto Semiconductors.pdf

http://www.osram-os.com/Graphics/XPic9/00063073_0.pdf/Details to the Assembly and Solder Pad Design of the OSLON, OSLON SSL and OSLON Square Family.pdf

http://www.osram-os.com/Graphics/XPic9/00102637_0.pdf/Temperature Measurement with Thermocouples.pdf

http://www.osram-os.com/Graphics/XPic6/00102526_0.pdf/Driving LEDs with a PIC Microcontroller.pdf

..upsss.... ...on other things... ..i see... 2 new pdfs (...and vids...) on the osram Led Fundamentals...
http://ledlight.osram-os.com/knowledge/led-fundamentals/
http://ledlight.osram-os.com/knowledge/led-fundamentals/

http://ledlight.osram-os.com/wp-content/uploads/2014/04/OSRAM-OS_LED-FUNDAMENTALS_Mesopic_Vision_v1_4-2-141.pdf

http://ledlight.osram-os.com/wp-content/uploads/2011/01/OSRAM-OS_LED-FUNDAMENTALS_Primary_and_Secondary_Optics_v4_03-1-14_SCRIPT.pdf


Pd ....upssss... ...I edit this post to not crush the post of sds...

...on the post..https://www.rollitup.org/t/how-to-reflow-leds-onto-star.820160/#post-10394895

...the image (and others i linked) is not available in the site... sorry... changes on the site...the list of the discontinued products increases fast... :cry:

...but I think you could understand the written description....:evil:


Pd 2 ...more tutorials...:clap:

https://www.sparkfun.com/tutorials/category/2

https://learn.sparkfun.com/tutorials/electronics-assembly

https://learn.sparkfun.com/tutorials/how-to-solder---through-hole-soldering

https://learn.sparkfun.com/tutorials/large-solderable-breadboard-hookup-guide/all


pd 3...to the moderator ....Sir you can erase this previous post..#12

...on the post..https://www.rollitup.org/t/how-to-reflow-leds-onto-star.820160/#post-10377505

...i linked bad to a vids...i prefer this way...


Soldering High-Brightness LEDs - Another Geek Moment


DIY home-made SMT metal stencil


Hot Plate LEDengin 10W Soldering .....now i dont like this video... but ...al carajo...


...go back to being invisible... ...or ignored... ...well.. im a loser baby... ..nothing new under my sun...:cool:


bye...

Saludos
 

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Positivity

Positivity

Well-Known Member
Little update...

Used this stencil to reflow the new cree photo red...
https://oshpark.com/shared_projects/dw8NYoED

Uploaded to oshstencil and ordered with a handy jig....http://www.oshstencils.com

Datasheet for cree xpe with reflow instructions towards last few pages....
http://www.cree.com/~/media/Files/Cree/LED Components and Modules/XLamp/Data and Binning/XLampXPE.pdf

Works well enough. Better than trying to do it free hand.

Stovetop works well enough. There are a few tricks that make it relatively easy.

I only do 4 stars at a time now. Two on either side of the temp probe. That's the only way I can be sure the temperatures are somewhat similar between all stars.

My stove dosent heat up very fast so it's basically turn it on high and let it go up to the max recommended temp for cree xpes...260C. I actually cut it to 250C and held temps on the shorter end of recommended because I noticed the first few sinkpads discolored a little.

I do turn off the burner for a few seconds a few times to slow it down a little. Typically at the ramp up phase and at the peak temp to hold it there for about 20 seconds. Then turn off the stove and remove the pan from element to achieve a slow cooling.

Gets easier every time. Buy extra if it's your first time.

Cree photo red on a copper sinkpad 2. Done with stencil from oshstencil, chipquik sac305 t5 paste solder, and hotplate with temp meter.

The photo of the solder paste after just being applied with stencil. That is about what I averaged with the stencil. It is a bit of a art form, like painting a canvas. I actually had it refined to what I thought a perfect amount at the end. Moral of the story...even with a stencil it takes practice. But I wouldn't want to do it without it.

image.jpg image.jpg image.jpg


Edit...
Looks like there's a nice Tc measurement point on these sinkpad 2 stars. Schweeeeet!!
 
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stardustsailor

stardustsailor

Well-Known Member
Positivity said:
Little update...

Used this stencil to reflow the new cree photo red...
https://oshpark.com/shared_projects/dw8NYoED

Uploaded to oshstencil and ordered with a handy jig....http://www.oshstencils.com

Datasheet for cree xpe with reflow instructions towards last few pages....
http://www.cree.com/~/media/Files/Cree/LED Components and Modules/XLamp/Data and Binning/XLampXPE.pdf

Works well enough. Better than trying to do it free hand.

Stovetop works well enough. There are a few tricks that make it relatively easy.

I only do 4 stars at a time now. Two on either side of the temp probe. That's the only way I can be sure the temperatures are somewhat similar between all stars.

My stove dosent heat up very fast so it's basically turn it on high and let it go up to the max recommended temp for cree xpes...260C. I actually cut it to 250C and held temps on the shorter end of recommended because I noticed the first few sinkpads discolored a little.

I do turn off the burner for a few seconds a few times to slow it down a little. Typically at the ramp up phase and at the peak temp to hold it there for about 20 seconds. Then turn off the stove and remove the pan from element to achieve a slow cooling.

Gets easier every time. Buy extra if it's your first time.

Cree photo red on a copper sinkpad 2. Done with stencil from oshstencil, chipquik sac305 t5 paste solder, and hotplate with temp meter.

The photo of the solder paste after just being applied with stencil. That is about what I averaged with the stencil. It is a bit of a art form, like painting a canvas. I actually had it refined to what I thought a perfect amount at the end. Moral of the story...even with a stencil it takes practice. But I wouldn't want to do it without it.

View attachment 3215499 View attachment 3215500 View attachment 3215501


Edit...
Looks like there's a nice Tc measurement point on these sinkpad 2 stars. Schweeeeet!!
Click to expand...
Looks like you did an awesome job,Master Reflower Pos !!
Congrats !
 
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